The disclosure herein relates to methods for coating substrates and coated substrates formed thereby. The coated substrates may be tablets or other forms for pharmaceutical use.
The need for controlled release and/or delayed release of pharmaceuticals arises in many instances and treatment protocols. The efficacy and uptake of various pharmaceutical compounds is enhanced in situations where the release or dissolving of the compound may be delayed to occur at a specific anatomical location and/or time interval. Additionally, the efficacy of certain pharmaceutical compounds is enhanced or regulated by the slow release of the compound or compounds over time. Various strategies have been developed for producing time-release pharmaceutical materials. Also, various strategies have been proposed for providing delayed release dose forms in which the active pharmaceutical agent is not released for uptake in the body until the dose form reaches a certain anatomical location. Thus, various coatings have been proposed for providing tablets that dissolve in the stomach, intestine, or other region.
Attempts have been made to produce a coated tablet or dose form that provides delayed dissolution over time. Some of these attempts include the random application of multiple coating compounds having different dissolution characteristics. In such instances, the coating compound is insoluble in a material, such as gastrointestinal fluid, and is doped with a soluble polymer such that the soluble polymer in the coating composition may selectively dissolve once the tablet reaches the stomach, thereby forming pores and initiating medication release. The coating process typically involves spray application of a solution containing the dissolved polymers over a drug core. The amount of pore formation and its position is a stochastic process. Thus, the number and density of potential pore locations may vary from dose form to dose form and from pharmaceutical batch to pharmaceutical batch.